Codec test program

My standalone codec test program is now available at [1]. That patch
includes a few changes to the rest of Rockbox to reduce dependencies. I
spent the last week cleaning it up and adding most of the features I
wanted.

It requires SDL and has only been tested on Linux. You should be able to
play files with:
cd /path/to/rockbox
patch -p1 < /path/to/patch
cd warble
make
./warble /path/to/musicfile

Run ./warble -h for a list of options. You can convert files to WAV:
./warble in.ogg out.wav

By default, this uses the DSP code to convert to 16-bit 44100Hz stereo.
If you want the exact output of the codec, you can use the -f option to
disable DSP and convert to 64-bit float instead. This preserves the full
accuracy of the codec, with the disadvantage that some common programs
(MPlayer) don't support 64-bit float.

There's also the -r option, which disables the WAV header and writes the
raw, unscaled 32-bit output from the codec. This is mostly useful piped
to a hash program for testing:
./warble in.ogg -r - | sha1sum